In a conventional single-point to fixed-multipoint data communication system, a base station transmits to fixed remote stations and each of the fixed remote stations, in turn, transmits to the base station. Such systems typically use one or more predetermined and typically internationally adopted communication protocols. These protocols tend to be optimized for particular applications and industries. For example, protocols used for wireless communication tend to be developed and influenced by the telecommunication industry. However, since many of these conventional systems that have communication media interconnecting the base station to the fixed remote stations are terrestrial (e.g., copper or optical fiber medium) the data communication protocols tend to be developed and/or heavily influenced by the computer industry.
A fixed wireless system is generally characterized by a point to multipoint topology where remote stations are fixed at specific locations. Wireless in the Local Loop (WLL) is an example of a point to multipoint topology. Most WLL solutions use a variant one of the major wireless telecommunication protocols such as Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), or Code Division Multiple Access (CDMA). Systems using these protocols assign and reserve bandwidth for the communication between the remote stations and the base station.
A FDMA-based system assigns a separate channel in an available channel band to each remote station. For instance, in cellular systems these channels are assigned by the base station upon receiving a request for channel from a cellular phone (radio). There is a common channel used for control information that is passed back and forth between the base and remote. A TDMA-based system breaks a channel into time slots. Each remote station is assigned a time slot. If there is no data to be transmitted when the time slot becomes available, the bandwidth is wasted since it is not reallocated to another remote radio. In general, a CDMA-based system uses a non-correlating coding sequence to allow multiple radios to transmit and receive in the same frequency range. In cellular CDMA, a base station assigns a code based on a request from a cell phone. There is a practical limit to the number of codes in use in a sector, thus limiting the number of active channels.
Conventional wireless telecommunication protocols tend to be efficient where there is a continuous flow of information. However, Internet data traffic and modern voice digitizing technology is by its nature bursty in its use of bandwidth. Accordingly, systems using these conventional protocols do not make efficient use of the available channel bandwidth with the bursty data traffic, largely because the assigned channels remain idle whenever their assigned stations are not bursting.
Another drawback associated with existing wireless telecommunications protocols is that they require a base station to communicate and broker bandwidth among the remote stations which causes significant delays. Additionally, these conventional protocols fail to accommodate the various demands of different remote stations at different times because of their inability to dynamically allocate bandwidth based on traffic demand.
Conventional computer-based data communication protocols are typically designed and used for multipoint to multipoint communication. Such protocol are optimized to handle bursty data traffic. Examples of such protocols include Carrier Sense Multiple Access (CSMA) and Carrier Sense Multiple Access/Collision Detection (CSMA/CD) protocols. When optimized, these protocols can make efficient use of the bandwidth. The optimization, however, assumes the multipoint-to-multipoint underlying topology. In addition, because of the lack of channel reservations and due to the inconsistency of burstiness of data traffic, these protocols fail to adequately support time sensitive data traffic, such as digitized voice, at high utilization rate of their bandwidth.